Energy use analysis in commercial buildings has been performed for many years by a number of software simulation tools which seek to predict the comfort levels of buildings while estimating the energy use. The underlying principles of these tools concentrate on thermal properties of individual elements of the building itself, such as wall panels, windows, etc. The complexity and level of detail required to accurately simulate a commercial building often makes its use prohibitive. The accuracy of such models has also been called into question in the research material. Following the construction and occupation of a new commercial building, the installed plant, such as boilers and air conditioning equipment, whose function is to provide suitable occupant comfort, is usually controlled by a building management system (BMS).
Through practical experience within the construction industry, it has become known that this plant is often over-sized and the use of the plant is often excessive. Common examples of this include plant operating for significantly longer than required including unoccupied weekends, heating and cooling simultaneously operating in the same areas due to construction or control strategy problems and issues with overheating and the use of cooling to compensate. Where the common problem of overheating occurs, the building envelope is quite efficient in dumping excess heat by radiation. In a similar manner, where buildings are over-cooled in summer, buildings are very effective in absorbing heat from the external environment to compensate. The utilization of this plant is not normally matched to the building envelope in which it operates and it is the intention to show how the method can help with this matching process.
The teachings in U.S. Pat. No. 8,977,405 and publication no. US2015-0198961-A1, provide a series of methods developed to provide a high-level view of thermal performance in a commercial building. This view is quick to implement and easily understood by facilities and maintenance staff. The methods facilitate a better understanding of the thermal performance of a building envelope, as constructed, and the interaction between this envelope and the building's heating and cooling plant, as installed. The thermal performance of the building envelope and how it interacts with the plant has been expressed as a series of time lags and profiles which are functions of external temperature and solar activity. External temperature remains the most influential of the external weather parameters on energy usage. The lags and profiles have been developed to be derived from data which is readily available within modern conventional buildings.